I did a few tests, and it seems to be blocking Proboards and Freeforums links. Forumotion and non-hosted website links are definitely not blocked, but it may be blocking all others, I'm not sure. Unless anyone has any suggestions, I will not be advertising on any boards except main website and Forumotion now, and if I advertised on your board but your link is being blocked, feel free to delete my ad.